• Applied Chemistry for Engineering
• /
• v.25 no.1
• /
• pp.90-95
• /
• 2014

Nylon66 extrudates as a function of the extrusion number were prepared by a twin screw extruder. Chemical structures, thermal properties, melt index, crystal structures, mechanical properties such as the tensile strength, elongation at break and impact strength, and rheological property were measured by FT-IR, $^1H$-NMR, melt indexer, DSC, TGA, XRD, universal tensile tester, Izod impact tester, and rheometer. FT-IR and $^1H$-NMR characterizations indicated that the number of extrusions did not affect the chemical structure. The decrease in the molecular weight was checked by the melt index of extrudates. There were no effects of the thermal history on the melting and degradation temperature. The tensile and impact strength and modulus were found to be similar, regardless of the number of extrusions, but the elongation decreased significantly. The complex viscosity of extrudates at low frequencies decreased with the extrusion number. No structural changes after extrusion were confirmed from the fact that there was no change in the slope and shape of G'-G" plot.

• Journal of Adhesion and Interface
• /
• v.12 no.3
• /
• pp.81-87
• /
• 2011

In this study, UV curing and crosslinking process was introduced for synthesis of acrylic foam tape that can be applied to the the automotive assembly process. Polymerized adhesive are laminated to baseform and varying the thickness of specimens were prepared. To measure basic mechanical properties, stainless steel was used. And in the test peel, dynamic shear and t-block were used. The acrylform adhesive show better results compare with typical adhesive and the properties depand on external factors - thick, wetting time -. To analysis functions of acrylic foam adhesive used to automobile production, evaluate the adhesive properties on the various plastic substrate. In PP and PE are categorized low surface energy materials, their properties have not been expressed. But dynamic shear tests show that some properties could be expressed by the difference break mechanism.

• Elastomers and Composites
• /
• v.38 no.1
• /
• pp.81-87
• /
• 2003

In this work, $Fe_3O_4$ (magnetite), conductive filler was prepared from $FeCl_2{\cdot}4H_2O,\;(CH_2)_6N_4$ (hexamethylene tetramine), and $NaNO_2$, followed by mixing with crystallizable chloroprene rubber(CR). The influence of conductive filler content on the properties of the conductive composite was studied and temperature dependence of the electrical conductivity (${\sigma}$) was also investigated. It is found that the percolation threshold concept holds true for the conductive particle-filled composite where ${\sigma}$ indicates a nearly sharp increase when the fraction of magnetite in the mixture exceeds 27%. The temperature dependence of ${\sigma}$ is thermally activated blelow or at the $P_c$. Magnetite acts as reinforcement and conductive filler for CR rubber. Moreover, it is shown that the composite with magnetite of 50 phr gives the most significant mechanical properties for tensile strength and elongation at break, which is due to the formation of optimum physical interlock and crosslinking. The results of 100%, 200%, and 300% moduli suggest that the moduli are related with reinforcement effect of magnetite and viscosity of the blend.

• Elastomers and Composites
• /
• v.38 no.3
• /
• pp.243-250
• /
• 2003

Polyurethane waterproof (PW) coatings are increasingly demanded in Korea for repairing cracks on old building roofs and construction of many sporting facilities. Calcium carbonate, a common filler, is incorporated in PW compositions. In this study, PW coatings were prepared by substituting a part of calcium carbonate with fly ash. The maximum amounts of calcium carbonate which can be substituted by fly ash obtained in the cyclone and bag filter dust collectors were 20 and 10%, respectively. It was found that the curing rate of PWs ran be controlled by varying the amount of Pb-octoate catalyst. The elongations at break as well as tensile strength and tear strength of PW coatings containing fly ash could also be adjusted such that their values were comparable to those of a standard PW coating by varying relative amounts of some components. However, the amount of cadmium, mercury, and lead leached from PW coatings containing fly ash obtained from the bag filter collector exceeded the respective allowed upper limits, mainly due to the initial high contents of them in the fly ash. On the other hand, PW coatings containing fly ash obtained from the cyclone collector exhibited better mechanical properties and did not release any significant amounts of the heavy metals. Thus, it was concluded that PW coatings containing fly ash can be utilized for practical applications as long as an appropriate fly ash is used.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.4
• /
• pp.23-32
• /
• 2023

The seismic performance of buried PE pipes is reported to be favorable due to their exceptional elongation capacity at break. Although a seismic performance evaluation procedure based on the response displacement method has been summarized in Korea for fusion-bonded PE pipes, there is currently no procedure available for mechanically jointed PE pipes. This article aims to present a seismic performance evaluation procedure based on the response displacement method specifically designed for mechanically jointed PE pipes in Korea. When employing the mechanical joining method for PE pipes, it is recommended to adhere to the evaluation procedure established for segment-type pipes. This involves assessing the stress induced by the pipe, the expansion and contraction strain of the joint, and the bending angle of the pipe joint. Furthermore, the coefficient of inhomogeneity of the soil, which is necessary for estimating the axial strain of the ground, is introduced. Additionally, a computation method for determining lateral displacement and reconsolidation settlement in soil susceptible to liquefaction is proposed. As a result of the sensitivity analysis considering the typical soil condition in Korea, the mechanically jointed PE pipe with a certain quality was shown to have good structural seismic safety when soil liquefaction was not considered. This procedure serves as a valuable tool for seismic design and evaluating the seismic performance of mechanically joined buried PE pipes, which are primarily utilized for connecting small-diameter pipes.

• Clean Technology
• /
• v.15 no.3
• /
• pp.172-179
• /
• 2009

The thermoplastic polyurethane waste (TPU-S) with good tensile properties, hardness, NBS abrasion resistance, specific gravity and low wet coefficient of kinetic friction was melt-blended with ethylene propylene diene monomer rubber (EPDM) with high wet slip resistance and low mechanical properties to form EPDM/TPU-S blend films, and their composition-property relationship was investigated to find the optimum composition for shoe outsole material. The properties except the wet slip resistance increased with increasing TPU-S contents in the blend. All the properties except elongation at break, specific gravity and the wet coefficient of kinetic friction in the range of $0{\sim}65\;wt%$ of TPU-S did not attain the values predicted by the simple additive rule. The optimum weight ratio of EPDM/TPU-S for the application to the typical shoe outsole material was found to be 30/70.

• Korean Journal of Food Science and Technology
• /
• v.30 no.5
• /
• pp.1097-1106
• /
• 1998

Biodegradable edible films were prepared from rice protein concentrates (RPC) made from rice wine meal by alkaline extraction and isoelectric precipitation. The effect of film forming solution pH and plasticizers were studied, and cross-linkers were added to improve mechanical properties and water vapor permeabilities (WVP) of films. Films could be formed within pH $8{\sim}11$ with tensile strength (TS) of 4.3{\sim}5.7\;MPa$. Films produced under pH 11 had the highest TS (5.7 MPa) and the lowest WVP $(0.44\;ng{\cdot}m/m^2{\cdot}s{\cdot}Pa)$. Added glycerol, polyethylene glycol 200 (PEG) and its mixture (GLY:PEG=50:50) as plasticizers also affected the mechanical properties and WVP of films. TS and elongation at break (E) of films at various plasticizer levels were $5.5{\sim}1.0\;MPa$ and $3.6{\sim}24.3%$, respectively. At the same plasticizer concentration, the highest TS was observed when glycerol was used whereas the highest E was measured when mixture was used as plasticizer. WVPs of films with thickness of $60\;{\mu}m$ were $0.39{\sim}0.54\;ng{\cdot}m/m^2{\cdot}s{\cdot}Pa$. WVP of films decreased as the ratio of glycerol/PEG 200 was decreased, and WVP increased as the total amount of plasticizer added to the films increased. Film strength was improved by the addition of small amount of sodium hydrogen sulfate, succinic anhydride, ascorbic acid and citric acid, whereas TS of films containing $0.5{\sim}2.0%$ of NaCl and $CaCl_2$ were lower than those without the salts. The highest TS (6.3 MPa) was achieved with films containing 0.1% of succinic anhydride.

• Journal of the East Asian Society of Dietary Life
• /
• v.18 no.3
• /
• pp.311-321
• /
• 2008

In order to improve the insufficient protein content of Jeung-Pyun with respect to sitology, as well as its fermentation process, this study prepared Jeung-Pyun doughs containing 0, 5, 10, 15, and 20 g of milk, respectively, and examined their mechanical and functional characteristics. The internal structure of the Jeung-Pyun was observed by SEM. With regard to color, the L-value increased with increasing amounts of added milk, and the highest value (65.43) occurred in the group containing 20 g of added milk; however, there were no significant differences among groups. The group containing 20 g of added milk also presented the highest a-value, and the samples with added milk had higher b-values than the control. At 8 hours of fermentation, the 10 g- and 15 g-added milk groups had viscosities of 5726.67 and 6600 respectively; viscosity increased with increasing amounts of milk, and the added-milk groups had significantly higher values than the control group. Hardness also increased with increasing amounts of added milk. However, there were no significant differences in resilience and cohesive power among the groups. The groups containing 5 and 10 g of added milk had the lowest cohesion and break values. For appearance, the group without added milk had the whitest color. Pore size decreased and showed less uniformity as the amount of added milk increased. The unique tackju aroma of Jeung-Pyun decreased significantly as the level of added milk increased, and the 20 g addition presented the lowest value. The 10 g-added milk group had the highest level of sweetness, and sourness increased with increasing amounts of added milk. For softness, the control group was estimated as slightly softer than the added-milk groups. The stickiest sample was generally preferred when considering taste, white color, and sweetness. Among the quality characteristics, having greater stickiness, resilience, moisture, and softness was better in terms of chewing. Overall, the size of the Jeung-Pyun containing 10 g of milk was even and well-developed.

• Journal of Practical Agriculture & Fisheries Research
• /
• v.11 no.1
• /
• pp.79-94
• /
• 2009

The research project was conducted to develop a paper bagging machine for grape. This technology was aimed to highly reduce a labor for paper bagging in grape and bakery. In agriculture labor and farm population has rapidly decreased since 1980 in Korea so there was so limit in labor. In particular there is highly population in women and old age at rural area and thus labor cost is so high. Therefore a labor saving technology in agricultural sector might be needed to be replaced these old age with mechanical and labor saving tool in agriculture. The following was summarized of the research results for development of a paper bagging machine for grape. 1. Development of a new paper bagging machine for grape - This machine was designed by CATIA VI2/AUTO CAD2000 programme. - A paper bagging machine was mechanically binded a paper bag of grape which should be light and small size. This machine would be designed for women and old age with convenience during bagging work at the field site. - This machine was manufactured with total weight of less than 350g. - An overage bagging operation was more than 99% at the actual field process. - A paper bagging machine was designed with cartridge type which would be easily operated between rows and grape branches under field condition. - The type of cartridge pin was designed as a C-ring type with the length of 500mm which was good for bagging both grape and bakery. - In particular this machine was developed to easily operated among vines of the grape trees. 2. Field trials of a paper bagging machine in grape - There was high in grape quality as compared to the untreated control at the application of paper bagging machine. - The efficiency of paper bagging machine was 102% which was alternative tool for the conventional. - The roll pin of paper bagging machine was good with 5.3cm in terms of bagging precision. - There was no in grape quality between the paper bagging machine and the conventional method. - Disease infection and grape break was not in difference both treatments.

• Korean Journal of Heritage: History & Science
• /
• v.37
• /
• pp.285-307
• /
• 2004

Synthesize and examine petrological characteristic and geochemical characteristic by weathering formation of rock and progress of weathering laying stress on stone cultural properties of Unjusa temple of Chonnam Hwasun county site in this research. Examine closely weathering element that influence mechanical, chemical, mineralogical and physical weathering of rocks that accomplish stone cultural properties and these do quantification, wish to utilize by a basic knowledge for conservation scientific research of stone cultural properties by these result. Enforced component analysis of rock and mineralogical survey about 18 samples (pyroclastic tuff; 7, ash tuff; 4, granite ; 4, granitic gneiss; 3) all to search petrological characteristic and geochemical characteristic by weathering of Unjusa temple precinct stone cultural properties and recorded deterioration degree about each stone cultural properties observing naked eye. Major rock that constitution Unjusa temple one great geological features has strike of N30-40W and dip of 10-20NE being pyroclastic tuff. This pyroclastic tuff is ranging very extensively laying center on Unjusa temple and stone cultural properties of precinct is modeled by this pyroclastic tuff. Stone cultural propertieses of present Unjusa temple precinct are accomplishing structural imbalance with serious crack, and because weathering of rock with serious biological pollution is gone fairly, rubble break away and weathering and deterioration phenomenon such as fall off of a particle of mineral are appearing extremely. Also, a piece of iron and cement mortar of stone cultural properties everywhere are forming precipitate of reddish brown and light gray being oxidized. About these stone cultural properties, most stone cultural propertieses show SD(severe damage) to MD(moderate damage) as result that record Deterioration degree. X-ray diffraction analysis result samples of each rock are consisted of mineral of quartz, orthoclase,plagioclase, calcite, magnetite etc. Quartz and feldspar alterated extremely in a microscopic analysis, and biotite that show crystalline form of anhedral shows state that become chloritization that is secondary weathering mineral being weathered. Also, see that show iron precipitate of reddish brown to crack zone of tuff everywhere preview rock that weathering is gone deep. Tuffs that accomplish stone cultural properties of study area is illustrated to field of Subalkaline and Peraluminous, $SiO_2$(wt.%) extent of samples pyroclastic tuff 70.08-73.69, ash tuff extent of 70.26-78.42 show. In calculate Chemical Index of Alteration(CIA) and Weathering Potential Index(WPI) about major elements extent of CIA pyroclastic tuff 55.05-60.75, ash tuff 52.10-58.70, granite 49.49-51.06 granitic gneiss shows value of 53.25-67.14 and these have high value gneiss and tuffs. WPI previews that is see as thing which is illustrated being approximated in 0 lines and 0 lines low samples of tuffs and gneiss is receiving esaily weathering process as appear in CIA. As clay mineral of smectite, zeolite that is secondary weathering produce of rock as result that pick powdering of rock and clothing material of stone cultural properties observed by scanning electron micrographs (SEM). And roots of lichen and spore of hyphae that is weathering element are observed together. This rock deep organism being coating to add mechanical weathering process of stone cultural properties do, and is assumed that change the clay mineral is gone fairly in stone cultural properties with these. As the weathering of rocks is under a serious condition, the damage by the natural environment such as rain, wind, trees and the ground is accelerated. As a counter-measure, the first necessary thing is to build the ground environment about protecting water invasion by making the drainage and checking the surrounding environment. The second thing are building hardening and extirpation process that strengthens the rock, dealing biologically by reducing lichens, and sticking crevice part restoration using synthetic resin. Moreover, it is assumed to be desirable to build the protection facility that can block wind, sunlight, and rain which are the cause of the weathering, and that goes well with the surrounding environment.